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More than just BMW is using it and not just in Europe. VW and Fiat introduced it in Europe in the '80s. Audi, Alfa Romero, and Citroën both use the technology. BMW started using it in 2008. It's being used in Japan by Toyota, Mazda, and Honda. I'm pretty sure that my friend's 2011 E90 M3 has it.

It's all about fuel efficiency and emissions. Manufacturers must meet ever increasing CAFE requirements and are pulling out all the stops to do whatever they can to reduce emissions and increase fuel efficiency.

On the F30 BMW's implementation includes a button under the start button that allows the driver to turn if off if they don't want to use it but it will be on by default.

The biggest problem with this technology is not the starter but the battery being discharged by having to restart the engine far more frequently.

I had auto start/stop on the 535i I drove in Europe. I must admit at first it was a bit creepy having the car go dead silent at the lights, but I quickly got used to it and actually rather liked it. The car sprung to life pretty damned quickly as soon as you let off the brake and got ready to hit the gas pedal... but I will warn you that jackrabbit starts from the lights are a no-no. I got hung up once or twice by the car being half a heartbeat behind me when trying to get around a left turn at a set of lights... sometimes quite scary when a truck is heading right for you.

Now, having said that after 10 days in Europe I was well accustomed to it and found it nice and relaxing to have the car shut off if I was at the lights long enough. It does get around the battery discharge problem because if the battery is too discharged it won't shut the engine off. Similarly if you're sitting at the lights for a REALLY extended time then the engine will fire up periodically to keep the battery charged.

The only real downside I found was that in combination with ComfortAccess it can confuse you a little. Once at a rest stop in Northern Germany I returned to the car after a few minutes to find it running. I had neglected to hit the stop button when I got out, and while I had locked the car, when I got out I didn't think about the engine because I didn't hear it running. Because it wasn't running, of course. I laughed, but I couldn't help but be a bit creeped out by the idea that if I had stopped in a bad neighbourhood and not locked it, someone could easily have driven away with the car even without the key.

Now, having said that after 10 days in Europe I was well accustomed to it and found it nice and relaxing to have the car shut off if I was at the lights long enough. It does get around the battery discharge problem because if the battery is too discharged it won't shut the engine off. Similarly if you're sitting at the lights for a REALLY extended time then the engine will fire up periodically to keep the battery charged.

This is what immediately came to mind when I first read about this technology being brought to the 3-series. BMW seems to have a problem keeping the battery charged with short trips. I can imagine this will extend the length of the trip necessary to keep the battery properly charged.

The only real downside I found was that in combination with ComfortAccess it can confuse you a little. Once at a rest stop in Northern Germany I returned to the car after a few minutes to find it running. I had neglected to hit the stop button when I got out, and while I had locked the car, when I got out I didn't think about the engine because I didn't hear it running. Because it wasn't running, of course. I laughed, but I couldn't help but be a bit creeped out by the idea that if I had stopped in a bad neighbourhood and not locked it, someone could easily have driven away with the car even without the key.

But I thought that the gear shifter doesn't move when the key is not present, at least that is how it works on my car with comfort access.

but I will warn you that jackrabbit starts from the lights are a no-no. I got hung up once or twice by the car being half a heartbeat behind me when trying to get around a left turn at a set of lights... sometimes quite scary when a truck is heading right for you.

How does this work with manual transmission cars? Does the car have to be in neutral? If so, I think it would work pretty well since one would be out of neutral when ready to go.

Also, the driver can prevent the Stop-start function on a case-by-case basis. Immediately after the car is stopped but before the function cuts the engine, forcefully pulse/push the brake pedal to the floor then quickly release.

It will exacerbate TO bearing failure in alot of cars, not so much in others. Largely due to TO bearing design - most last longer than the life of the clutch, so it's not even a concern, but I know in my Legacy GT the TO bearings have been known to fail early and tear apart the transmission input shaft.

Anyway, if stop/start works upon clutch pedal depression/gear selection, then I'm good to go with it. I shift into 1st gear a few seconds before I want to take off from a stop, so the engine will be back on and won't "slow me down".

I sit at long lights/stops in neutral. No reason to have my throwout bearing spinning when I can easily observe there's no where to go in the next few seconds.

I've never had a problem with TO bearings. I'm not opposed to changing the way I sit at traffic lights to gain the benefit of the auto stop/start. I suppose if my car had a heavy clutch, I wouldn't drive the way I do now.

Can anyone who's driven a BMW with Auto Start/Stop confirm with certainty whether it uses the starter to restart the engine or if it just fires the appropriate next cylinder and restarts the already warmed up engine that way? I was under the impression they used the 'next cylinder' method, but comments earlier in this thread seem to imply the starter method.

Can anyone who's driven a BMW with Auto Start/Stop confirm with certainty whether it uses the starter to restart the engine or if it just fires the appropriate next cylinder and restarts the already warmed up engine that way? I was under the impression they used the 'next cylinder' method, but comments earlier in this thread seem to imply the starter method.

I can't confirm which method it uses to restart the engine since I didn't really get into the technical details of the car. However, I will say that it starts VERY quickly when you goose the gas pedal. I think the delay between complete silence and accelerating was less than the turbo lag I had in my old Saab 900 Turbo... but that's probably not saying much.

Generally I found if I was driving reasonably sedately then the auto start/stop was never an intrusion. It did however mean that I was having to plan ahead if I wanted to drive it harder... something that still sits wrong with me a little. The benefit to me of buying a sports car/sedan is simply the ability to switch personality just by choosing to drive it differently. Having to hit buttons or think about how I'm driving in advance somehow just seems wrong.

So instead of a dynamic personality, I feel the auto start/stop as well as the buttons in the console give the cars more of a "switchable personality". Somehow I feel something has been lost there.

I can't confirm which method it uses to restart the engine since I didn't really get into the technical details of the car. However, I will say that it starts VERY quickly when you goose the gas pedal. I think the delay between complete silence and accelerating was less than the turbo lag I had in my old Saab 900 Turbo... but that's probably not saying much.

Generally I found if I was driving reasonably sedately then the auto start/stop was never an intrusion. It did however mean that I was having to plan ahead if I wanted to drive it harder... something that still sits wrong with me a little. The benefit to me of buying a sports car/sedan is simply the ability to switch personality just by choosing to drive it differently. Having to hit buttons or think about how I'm driving in advance somehow just seems wrong.

So instead of a dynamic personality, I feel the auto start/stop as well as the buttons in the console give the cars more of a "switchable personality". Somehow I feel something has been lost there.

Thanks Thumper! That super-quick start is consistent with what I've heard from others. That seems to me that it must be a 'fire next cylinder' start to get it running again that quickly, but I suppose the starter could get a warmed engine running pretty quickly as well.

Regardless, I have my 335i ordered and can hardly wait for my March 1 ED. If I don't like the way the start/stop operates, I'll just grow accustomed to hitting the start button and then immediately hitting the override button next to it. :-)

I believe they use the starter (I'm not sure how you'd fire the next cylinder without using a starter to move the piston- the stroke goes fuel spray, compress, fire - so you can't simply ignite fuel that's sitting on the cylinder walls and you can't have it spray and compress without moving the piston - so no matter what you need a starter to get that going...)

I believe they use the starter (I'm not sure how you'd fire the next cylinder without using a starter to move the piston- the stroke goes fuel spray, compress, fire - so you can't simply ignite fuel that's sitting on the cylinder walls and you can't have it spray and compress without moving the piston - so no matter what you need a starter to get that going...)

It is definitely possible to do it without using a starter motor. The computer determines the best positioned cylinder, it shoots a fresh shot of gas in, and fires the plug and then just keeps on firing the other cylinders as normal. The only good professional explanation I can locate quickly at the moment is a PDF, but here's a link: http://www.etas.com/data/RealTimes_2...6_01_34_en.pdf

Huh, I usually consider ignition at an improperly timed piston movement to be called "detonation" - but i guess it makes sense with the computer controlling the cylinder and the amount of fuel (presumably) it makes sense.